The FBI raided my neighbor’s house a few years ago. They rolled up in several cars before the break of dawn, pulled the neighbor out of the shower at gunpoint and his wife out of bed. They interrogated him for three hours, then rolled away with his computers, cameras and papers.

The neighbor is a mathematician — a brilliant one, according to the press — who worked for the National Security Agency (NSA). Many in my neighborhood do, as it’s headquartered less than two miles away. NSA is the federal agency responsible for keeping US intelligence communications secret while collecting and processing intelligence information from other countries. It also administers the only public museum in the Intelligence Community: the National Cryptologic Museum.

There are several guarded roads that I pass, in the course of an average day, that provide restricted access to NSA. I was going to say that I went to the National Cryptologic Museum last week to learn exactly what my neighbors do for a living but really, I wanted to know where those roads led. The directions on the museum’s website took me onto one of them (no police guards during museum hours) toward NSA. I edged the NSA employee parking lot, passed some airplanes and a gas station, and ended up in the museum parking lot.

I generally don’t write about stand-alone museums – warehouses of objects isn’t my definition of “historic site” – but I’m stretching the definition for the National Cryptologic Museum because it’s on the NSA campus and in an old office building. The museum has three missions. I’m only going to mention one, since it’s the only one that matters here: to document the history of cryptology. Cryptology is the science of creating and deciphering code.

I picked up a map of the museum and the phone number of the museum’s cell phone tour at the reception disk. The museum is five small rooms with displays grouped chronologically.

My favorite stories:

Thomas Jefferson — I just can’t seem to get away from him — invented a wheel cypher, now called the Jefferson Cylinder, which used sets of disks printed with the alphabet on its edge to scramble messages. The key to deciphering the message depended on knowing in exactly what order the sender set the disks on the axel. Necessity was the mother of his invention: he had to use code in his correspondence when he was minister to France, because French postmasters read all the mail.

Civil War combatants used flags to send coded signals. This was called “wig-wagging.” Since wig-wagging was hard to see from the ground, the army decided to send signalmen up in tethered balloons to deliver the signals. But there was one small problem: if one side could see a high flying balloon, so could the other. A well-placed shot and down went the balloon. They moved on to wooden towers.

In 1917, Arthur Zimmermann, the Imperial German foreign minister sent a message to the German ambassador to Mexico. The telegraph revealed a German plan for unrestricted submarine warfare and instucted the ambassador to seek a Mexican alliance if this caused the US to enter WWI on the Allied side. The Germans would promise New Mexico, Arizona and Texas to Mexico in return for their support. The British intercepted the message, decoded it, and showed it to the Americans. Americans were initially skeptical but the message proved real, and the US entered WWI soon after.

WWI also saw the start of Native American code talking: the use of Native Americans to exchange messages in their native language — languages that few outside of their own people understood. The most famous of the code talkers were the Navajo who joined the Marines during WWII. But the Choctaw during WWI and II, and the Cherokee, Lakota, and Comanche in WWII, also served.

As I left the museum, I saw a sign across the parking lot that said, “National Vigilance Park.” I took the path next to the sign through some woods and came out in a park populated with the planes I’d seen on my drive to the museum.

The National Vigilance Park honors those who served on aerial reconnaissance missions. It features three planes associated with the three branches of the military that conducted signal intelligence. The Army’s RU-8D served in Vietnam. The Navy’s EA-3B and the Air Force’s C-130A served against the Soviets during the Cold War.

The reason for the early morning raid on my neighbor’s house: he had been one of a group of NSA employees who had complained about problems at NSA – waste, abuse, incompetence – associated the development of a domestic spying project called Trailblazer. They took their concerns to the House Intelligence Committee and with Committee staff support, to the Department of Defense Inspector General. When that went nowhere, they went to the Baltimore Sun newspaper, which published a series of Pulitzer Prize winning reports based on their information. NSA was not as thrilled as the Pulitzer committee about the information going public.

What the NSA employees called whistleblowing, the NSA called treason. My neighbor and most of his coworkers were never charged, but his boss, Thomas Drake, was. Drake’s defense was that none of the information given to the reporter was secret and eventually, all charges except one (a misdemeanor for exceeding authorized use of a computer) were dropped. If you’re interested in the details of the case, they can be found in this New Yorker article.

I like museums too. I’m trying to be disciplined about limiting the scope of this blog though. If I let myself, I’d be jumping all over the place.

There were signs everywhere about there being cameras for our security, or something like that. I did wander through a conference room before I realized that it wasn’t part of the exhibit space. If the FBI come after me, I’ll know why.